Cyclic acetals of alpha-oxocarboxylic acid derivatives

ABSTRACT

Cyclic acetals of the formula   WHERE R1 is hydroxy, alkoxy, or NHZ, Z is hydrogen, alkyl, cycloalkyl, benzyl, or optionally substituted phenyl, R2 is hydrogen or alkyl, R3 is alkyl, and R4 is aralkyl, are useful as herbicides.

United States Patent [19 Kirby et al.

[ Jan. 28, 1975 CYCLIC ACETALS OF ALPHA-OXOCARBOXYLIC ACID DERIVATIVES [75] Inventors: Peter Kirby; Eirlys R. Isaac, both of Kent. England [73] Assignee: Shell Oil Company, New York. NY.

[22] Filed: May 18, 1972 [2]] Appl. No.1 254,536

[30] Foreign Application Priority Data May 27, I97] Great Britain"; l7564/7] [56] References Cited UNITED STATES PATENTS 8/l965 Fuzesi et al 260/340] l/l97l Pfeiffer at al. r, 260/3409 3,686,238 8/1972 Zul'laroni 260/3409 X Primary Examiner-Donald G. Daus Assistan! Examiner-James H. Tulrnipseed [57] ABSTRACT Cyclic acctals ol the formula where R is hydroxy, alkoxy, or NHZ, Z is hydrogen alkyl, cycloalkyl, benzyl, or optionally substituted phenyl, R is hydrogen or alkyl, R;, is alkyl, and R is analkyl, are useful as herbicides.

5 Claims, No Drawings 1 2 CYCLIC ACETALS OE ALPHA-OXOCARBOXYLIC R is methyl, ethyl, or propyl; and R, is benzyl, or (b) ACID DERIVATIVES those of formula H where R, is hydroxy, ethoxy, or a group of formula -NHZ, where Z is hydrogen or phe- BACKGROUND OF THE INVENTION nyl; R and R are each methyl; and R, is benzyl.

1. Field of the Invention 5 A particularly preferred class of compounds, having This invention relates to a novel class of cyclic acea high degree of herbicidal activity, are those of fortals of alpha-oxocarboxylic acid derivatives, to herbimula l where R, is phenylamino and R is methyl. cida'l compositions containing them, and to their use as Those derivatives of formula I or ll where R, is alkherbicides. oxy are prepared by a process which comprises react- 2. Description of the Prior Art It) ing an alkyl ester of an a-oxocarboxylic acid, or non- A search of the prior art indicates the herbicidal cycyclic acetal thereof. with the appropriate substituted clic acetals within the scope of this invention to be propane diol, in the presence of an anhydrous acid catnovel. alyst, for example hydrogen chloride or boron trifluo ride. SUMMARY OF THE INVENTION IS The derivatives where R, is hydroxy are prepared by It has now been found that certain novel cyclic acesaponifieation of the derivative where R, is alkoxy, ustals of alpha-oxocarboxylic acid derivatives exhibit ing, for example, a strong base such as sodium hydroxhigh herbicidal activity in the control of certain ecoide and liberating the acid from the salt so obtained by nomically important grass weed species. treatment with a mineral acid, such as hydrochloric acid. g gg fi igg The compounds where R, is a-gjroup of formula: The present invention relates to cyclic acetals having one or the other of the following isomeric formulae: are obtained by reacting the corresponding compound CUR s t 2-0 l I R3-i3-0 R2 (I) n -T-o1a/\ (11) where R, is hydroxy or alkoxy or a group of formula: where R, is alkoxy or acyloxy, for example alkoxycar- 35 NHZ bonyloxy, with a compound of formula.

in which Z is hydrogen, alkyl, cycloalkyl or benzyl, phe- NHZZ nyl-substituted amino, or phenyl optionally substituted When R, is phenyl-substituted amino the compound is by one or more halogen, alkyl, or alkoxy groups; R, is conveniently obtained by reacting the corresponding hydrogen or alkyl; R, is alkyl; and R is aralky]. 40 compound where R, is hydroxy with phenyl- Prefcrred cyclic acetal derivatives are (a) those of phosphazoanilide.

formula I where R, is hydroxy, alkoxy of 1-6 carbon The cyclic acetal derivatives of the invention are of atoms, for example ethoxy, or a group of formula: interest as broad spectrum herbicides particularly NHZ against grass weed species. The invention includes therefore herbicidal compositions comprising a carrier in which Z is a hydrogen atom, alkyl or cycloalkyl up or a surface-active agent, or both a carrier and a surto 6 carbon atoms, for example butyl or cyclohexyl, faceactive agent, and, as active ingredient, at least one benzyl, phenylamino, or phenyl optionally substituted cyclic acetal derivative of formula l or II. Likewise the by a fluorine atom, by one or two chlorine atoms, by invention includes also a method of combating weeds one or two alkyl groups of l-6 carbon atoms, for examat a locus which comprises applying to the locus a herple methyl, or by an alkoxy group of l-6 carbon atoms, bicidally effective amount of a cyclic acetal or compofor example methoxy; R is hydrogen or alkyl of l-6 sirion of the inventio carbon atoms, for example methyl; R is alkyl of l-6 The term carrier as used herein means a solid or carbon atoms, for example methyl, ethyl or propyl, and fluid material, which may be inorganic or organic and R, is benzyl, or (b) those of formula ll where R, is hyof synthetic or natural origin, with which the active droxy, alkoxy of l- -6 carbon atoms, for example ethcompound is mixed or formulated to facilitate its applioxy, or a group of formula: cation to the plant, seed, soil or other object to be treated, or its storage, transport or handling.

Suitable solid carriers are natural and synthetic clays in which Z is hydrogen or phenyl; R, and R each indeand silicates for example natural silicas such as diatopendently is alkyl of l-6 carbon atoms, for example maceous earths; magnesium silicates, for example,

methyl; and R is benzyl. tales; magnesium aluminum silicates, for example, at-

Particularly herbicidally active compounds of this intapulgites and vermiculites; aluminum silicates, for exvention (a) those of formula I where R, is hydroxy, ethample kaolinites, montmorillonites and micas', calcium oxy, or a group of formula -NHZ, in which Z is hydrocarbonates; calcium sulfate; synthetic hydrated silicon gen, butyl, cyclohexyl, benzyl, phenylamino, fluorooxides and synthetic calcium or aluminum silicates; elephenyl, chlorophenyl, dichlorophenyl, tolyl, dimethylments such as for example, carbon and sulfur; natural phenyl. or methoxyphenyl; R is hydrogen or methyl; and synthetic resins such as, for example, coumarone resins, polyvinyl chloride and styrene polymers and copolymers; solid polychlorophenols; bitumen, waxes such as for example, beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilizers, for example superphosphates.

Examples of suitable fluid carriers are water, alcohols, such as for example, isopropanol, glycols; ketones such as for example, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic hydrocarbons such as for example, benzene, toluene and xylene; petroleum fractions such as for example, kerosene, light mineral oils; chlorinated hydrocarbons. such as for example, carbon tetrachloride, perchloroethylene, trichloroethane, including liquified normally vaporous gaseous compounds. Mixtures of different liquids are often suitable.

The surface active agent may be an emulsifying agent or a dispersing agent or a wetting agent; it may be nonionic or ionic. Any of the surface-active agents usually applied in formulating herbicides or insecticides may be used. Examples of suitable surface-active agents are the sodium or calcium salts of polyacrylic acids and lignin sulfonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohols or alkyl phenols for example p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulfates or sulfonates of these condensation products, alkali or alkaline earth metal salts, preferably sodium salts, or sulfuric or sulfonic acid esters containing at least 10 carbon atoms in the molecule, for example, sodium lauryl sulfate, sodium secondary alkyl sulfates, sodium salts of sulfonated castor oil, and sodium alkylaryl sulfonates such as sodium dodecylbenzene sulfonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may be formulated as Wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders are usually compounded to contain 25, 50 or 75% by weight of toxicant and usually contain in addition to solid carrier, 3l07? by weight of a dispersing agent and, where necessary. -10% by weight of stabilizer(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar composition to that of a Wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing /2 by weight of toxicant. Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676 0.152 mm), and may be manufactured by agglomeration or impregnation techniques. Generally granules will contain /2 25% by weight toxicant and O 10% by weight of additives such as stabilizers, slow release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to the solvent and, when necessary, co-solvent, l0-50%weight per volume toxicant, 220% weight per volume emulsifiers and O20% weight per volume of appropriate additives such as stabilizers, penetrants and corrosion inhibitors. Suspension concentrates are compounded so as to obtain a stable, non-sedimenting, flowable product and usually contain 10-75% W toxicant, 0.5 w of dispersing agents, 0.1 10% w of suspending agents such as protective colloidsand th ixotropic agents, 0 10% w of appropriate additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and as carrier, water or an organic liquid in which the toxicam is substantially insoluble; certain organic solids or inorganic salts may be dissolved in the carrier to assist in preventing sedimentation or as antifreeze agents for water.

Aqueous dispersions and emulsions, for example, compositions obtained by diluting a Wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention. The said emulsions may be of the water-in-oil or of the oilin-water type, and may have a thick mayonnaise-like consistency.

The composition of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, especially insecticidal. acaricidal. herbicidal or fungicidal, properties.

The invention is further illustrated'in the following examples.

In the examples below, the structure of all the products prepared was confirmed by elemental analysis.

EXAMPLE 1 Ethyl 4-benzyloxymethyl-2,4-dimethyl-l ,3-dioxolan-2- carboxylate Dry hydrogen chloride gas was passed into a mixture of 3-benzyloxy-2-methylpropane-1,2-diol (14.9 grams) and ethyl pyruvate (9.15 grams) for 1 hour. The mixture was heated at C for a further 1 hour and then cooled to 50C. Benzene milliliters) was added to the mixture and the water formed in the reaction was removed azeotropically. The cooled solution was washed with potassium carbonate solution and dried. The solvent was removed under reduced pressure and the residue was fractionally distilled to yield the desired product boiling point l24126C at 0.3 Torr.

EXAMPLE 2 4-Benzyloxymethyl-2,4-dimethyl-l ,3-dioxolan-2- carboxylic acid Ethyl 4-benzyloxymethyl-2,4-dimethyl-l,3-dioxolan- 2-carboxylate (7.0 grams, prepared as in Example 1) was stirred with a solution of sodium hydroxide (1.0 grams) in water (50 milliliters) at 90C for 4 hours. The alcohol formed was removed under reduced pressure. The aqueous residue was washed twice with ether and acidified with 2M hydrochloric acid (10 milliliters). The mixture was extracted with ether and the extracts were washed, dried (MgSO,,) and evaporated under reduced pressure. The residue was fractionally distilled to give the desired product boiling point C at 0.1 Torr.

EXAMPLE 3 4-Benzyloxymethyl-2,4-dimethyl-l ,3-dioxolan-2-(N- phenylcarboxamide) 4-Benzyloxyrnethyl-2,4-dimethyl-1,3-dioxolane-2- carboxylic acid (3.0 grams, prepared as in Example 2) and phenyl phosphazoanilide (1.13 grams, prepared by the reaction of phosphorus trichloride with aniline) in toluene (25 milliliters) were heated together under reflux for 2 hours. The mixture was filtered and the residue was washed with hot toluene. The toluene was removed under reduced pressure and the residue was taken up in chloroform. The solution was shaken with 5% aqueous sodium bicarbonate solution and then with water and dried (MgSO The solvent was removed under reduced pressure and the residue purified by chromatography on silica gel using chlorofrom as eluant to give the desired product melting point 53-60C. (isomer mixture).

EXAMPLE 4 4-Benzyloxymethyl-2,4-dimethyl-l ,3-dioxolan-2- carboxamide Ethyl 4-benzyloxymethyl-2,4-dimethyl-l.3-dioxolan- Z-carboxylate (5.0 grams) and concentrated aqueous ammonia solution (50 milliliters. 0.880 5.6.) were stirred together at room temperature for 3 days. The white solid formed was filtered off, washed with water and recrystallised from cyclohexane to give the desired product as an isomer mixture melting point 72-92C.

EXAMPLE 5 4-Benzyloxymethyl-2,4-dimethyll ,3-dioxolan-2-( N- butylcarboxamide) Triethylamine (3.2 grams) was added to a solution of 4-benzyloxymethyl2,4-dimethyl-1,3-dioxolan-2- carboxylic acid (8.0 grams) in dry tetrahydrofuran (50 milliliters) maintained at 0-5C. The mixture was stirred for minutes and isobutyl chloroformate (4.1 grams) was added while the temperature of the mixture was maintained at 5-l0C. The stirring was continued for a further minutes. Butylamine (2.2 grams) was then added and the mixture stirred for l6 hours at room temperature. The mixture was then filtered and the filtrate was evaporated under reduced pressure. The residue was dissolved in ether and the solution was washed in turn with 2M hydrochloric acid, 5% sodium bicarbonate solution and water. The solution was then dried and the solvent was removed under reduced pressure. The residue was purified by chromatography on silica gel using chloroform as eluant to give the desired product as an oil R,(CHC1;,) 0.2.

EXAMPLE 6 Ethyl 4-benzyloxymethyl-4-methyl-l ,3-dioxolan-2- carboxylate 3-Benzyloxy-2-methylpropane-Il ,2-diol (19.6 grams), ethyl diethoxyacetate (17.6 grams) and boron trifluoride etherate (2milliliters) were heated together with stirring in a distillation apparatus. Heating was continued until ca 9.0 grams ethanol had been collected. Chloroform (100 milliliters) was added to the cooled residue and the solution obtained was washed first with 5% aqueous potassium carbonate solution and then with water. The solution was dried (MgSO and the solvent was removed under reduced pressure. The residue was purified by fractional distillation followed by chromatography on silica gel eluting with toluene and then 5% ether in toluene. The desired product was obtained as an oil R,(CHCl 0.39.

EXAMPLE 7' Following procedures analogous to those of the previous examples further compounds were prepared, whose physical characteristics and analyses are set out in Table l. The R values given for certain of the compounds were obtained by thin layer chromatography on coated silica gel plates (5X10 cm) with a layer thickness 0.25 mm using the solvents indicated. In certain cases where a mixture of geometrical isomers was obtained the individual isomers were separated by fractional crystallization.

TABLE 1 Compound Melting Point or Boiling Point C. or R,(solvent) S-benzyloxy-2,5-dimethyll ,3-dioxane-2-( N-phenylcarboxamide) (isomer mixture) ethyl 5-benzyloxy-2,5-dimethyl-l,3-dioxane-2- carboxylate 5-benzyloxy-2,5-dimethyl-l ,3-dioxane-2-carboxamide 5-benzyloxy-2,5-dimethyl-l ,3-dioxane-2-carhoxylic acid N-(Lbenzyloxymethyl-ZA-dimethyl-l ,3-dioxolanc- Z-yUcarbonyl )-N -phenylhydrazide 4-benzyloxymethyl-2,4-dimcthyl-l ,3-dioxolane- 2-( N-cyclohexylcarboxamide) 4-benzyloxymethyl-2,4-dimcthyl-l ,S-dioxolanc- 2-( N( 2,4-dichlorophcnyl )carboxamicle) 4-bcnzyloxymethyl-2,4-dimethyl-l ,3-dioxolane- 2-( N-( 2,4-dimcthylphenyl )carboxamide) ethyl 4-benzyloxymethyl-4-cthyl-2-methyl-l,3-

dioxolane-Z-carboxylate melting point boiling point l38 at 0.2mm Hg melting point 122 -l25 melting point 104 109 melting point 64 69 boiling point l34 at 0.4mm Hg R, (CHCl -fl 0.53

Table 1-Continued Compound Melting Point or Boiling Point C. or R,(solvent) 4-benzyloxymethyl-4-cthyl-2-methyll .3-

dioxolane-Z-carboxylic acid 4'benzyloxymethyl-4-ethyl-2-methyll .3-

dioxolane-2-( N-phenylcarboxamidc) (isomer 1 4-benzyloxymethyl-4-ethyl-2-mcthyl' l ,3-

dioxolane 2-( N-phenylcarboxamidc) (isomer 2) ethyl 4-benzyloxymcthyl-Z-methyl-4-propyl- V l,3-dioxolane-Z-carboxylate 4-benzyloxymethyl-2-methyl-4-pr0pyl-l ,3-

dioxolane-Z-carboxylic acid 4-benzyloxymethyl-2-mcthyl-4-propyl-l .3- dioxolune-2-( N-phenylcarhoxamide) (isomer l 4-henzyloxymethyl-2,4-dimethyll .3-dioxolane- 24 N-( 4-chlorophenyl )carhoxam idc) (isomer mixture) 4-henzyloxymethyl-2.4-dimcthyll ,3-dioxolane- 2-( N-( 4-fluorophenyl )carboxam idc) (isomer mixture) 4-benzyloxymethyl-2.4-dimethyl-l ,3-dioxolanc- 2-( N-p-tolycarboxamide) (isomer l 4-benzyloxymethyl-2,4-dimethyl-l ,3-dioxolane- 2-( N-4-methoxyphenyl )carboxamide (isomer 1 4-benzyloxymethyl-2,4-dimcthyl-l ,3-dioxolane- 2-( N-( 4-methoxyphenyl )carboxamidc (isomer 2) 4-benzyloxymethyl-2,4-dimcthyl-l ,3-dioxolane- 2-( N-o-tolylcarboxamide) 4-henzyloxymcthyl-2,4-dimethyll .3-dioxolane- 2 N-( Z-chlorophcnyl )carboxamide) -nzyloxymcthyl-2,4-dimcthyl-I .3dioxolane- N-t Z-methoxyphenyl )carhoxamide) 4henzyloxymethyl-ZA-dimethylj-dioxolane- 2-( N-( ."Lmcthoxyphenyl )earboxamidc) 4-bcnzyloxymcthyl-ZA-dimtfthyl-l ,3-dioxolane- 2-( N-m-tolycarhoxamidc) 4-bcnzyloxymethyl-2.4-dimethyl-l ,3-dioxolane- 2-( N-( 3-chlorophcnyl )carboxam idc) boiling point 156 at 0.2mm Hg melting point 102 106 melting point 65 67 boiling point 132 at 0.1 mm Hg R (2.5% ether/CHCl two isomers 0,14)

melting point melting point 55 Q9 (CHCI melting point 80 87 melting point 5 7 melting point 83 85 melting point melting point 96 9X melting point 79 81 RACHCM) RACHCI 0.58

EXAMPLE 8 Herbicidal Activity post-emergence. The pre-emergence tests involved spraying a liquid formulation of the compound onto the soil in which the seeds of the plant species mentioned above and recently been sown. The post-emergence tests involved two types ottest, viz. soil drench and foliar spray tests. In the soil drench tests the soil in which seedling plants of the above species were growing, was drenched with a liquid formulation containing a compound of the invention, and in the foliar spray tests the seedling plants were sprayed with such a formulation.

The soil used in the tests was a stream-sterilised, modified John lnnes Compost mixture in which half the m 00 CO CO CO CO OO O H4O RIO QC m o a H o o o m H w o o H I H H H... H H H n w m w c H c c L a w m w H: H HHHSH HHEQ H Y V Z I H a H m m o o o o m H Q H H. H H H H m w H m H c o c c c H c H H 5 5 5 50 HH QHHOHHZ H c N a H H m H H o H H a n H. a a H1. H. w H. l m w H H c a w w w OH H .EEom v Z H a o o m o o o o o o a o 7 H I' I; I, c o a m o m H w H w m m o o o o o o o 0H HHU HHOAHHO HHO $6 00 H H m H H a H H o o o o o o o H H m m w H. H w H u w m w m H H w o o w H H 2 E5 E0 a v HH OHHZ H H H H w a H w H m w c w H H. H H x w a a H. Q m H H H H. H w H H m w H H OH 56 E0 HH 6 HH OHHZ H o H o o m H o o o o o o o o I H v I I I v v v I I I v I I I I i. w w H m H H m m H w m H H m o o o o o o 0 0H HH O HHO HHO H a H c o a H o H H H o H o H 1 H 1.. 1 1. H e m m o a a m w w m a m o o m H o w H m S H HO HHO HH O HHOHHZ H o o o o H o o o H o o c o H I H A .i N m m o a m H w m w m H. m m H H H o o H H oH HH D HHO HHH OO H c o o o o o H m H o c o o .1 H I m o o a o o H o w m w m H o o o o m o o @H H HO HHO HH HHo H H vHHH/H I. H o o o w o o o m H H o o o f H m w m a w H m a w N H m w c H" O o H H o S HHo HHO HHO H HHOVHHZ H o o o H o o H m o H H m HHO w H o w m H c o o o o o o H o w w a o w o o o o o c Q o o o o w m H oH HHU c o o w m m o o H o o o o I H m H m m w w H H w H n o H oH HHU o o 0 Q o o o o o o o o o I H c H c H c o o w H m m H H o o o o o o o 0H HHO m N H a o o o c H H H o o 7 H m H w m m H m c w H. H H m o m H m m m c @H HHU m Q w a w m o H o m H H m I H w H w o m w H H H m w o H 1 0H HHO a a o o o o o o o o o o o H w c o H m o H m w H m c H o a o o o o o 0H WHO o o o w o H o o o c m o o H o H o a a H H o a H w o m o m o o w o H oH HHU 2 H H UHH HH 2 HHw H H H H OH NH H H Hm H H H H UMH NH H H 3H NH 5H H HH .35 :cm HHEHHW H Q H HZH V ow HHHHSHHEQO ouHHwmHwEw SHSmHQEH m HHHV 8 HH O HHO Eo HHooHHw O HH O HHOO O SH 3H O O HHH M 00 0 E0 JHOO O HHO MH HMHHTH.

M w W M m m m m M w W m m m w w m. w: 0 "m0 AEQSEPS VGQZ H M M. M 1% w m m m w m w M m w M m m w m ww M: D QEELSE H M n m m m w m m m m m M M 6 m w ww w Mi "m0 czcosamwofiwflz v z A m M m m m w m m M M w W m HW M m w M: 5 zhsosmhwoemi mvmz w w MW w w w m w w m fi w m v m w m m A HO "HO Q -$:QoHo u mVm H m w w m w m m w H N: 230732 w M. m w .mi! W m m. m m A? ":0 0 3.355.8505 :zz FQ Ei NM w a o a m S Q :0 17.... fi EEmms 229 52% W w m m m m w w m M m M My m mw flv w M: "i0 ":0 3.8536 QZOIC M. w m m w a w m m m w 6 m M AW M W W M; ":0 :0 QESgQcSE E m m 2 Q a m am 2 Q A :m m 5 n w 2 4 L U: m 5 E Q m 52 hcawmow aaawunzo 225 352550 QBEWEEYE 025325-30;

peat. by loose bulk, had been replaced by vermiculite. The formulations used in the tests were prepared by diluting with water and solutions of the compounds in acetone containing 0.4% by weight of an alkylphenol- /ethylene oxide condensate available under the trade name Triton X-l55. In the soil spray and foliar spray tests the acetone solutions were diluted with an equal volume of water and the resulting formulations applied at two dosage levels corresponding to l and 1 kilograms of active material per hectare respectively in a volume equivalent to 400 liters per hectare. In the soil drench tests one volume of the acetone solution was diluted for 155 volumes with water and the resulting formulation applied at one dosage level equivalent to kilograms of active material per hectare in a volume equivalent to approximately 3,000 liters per hectare.

in the pre-e mergence tests untreated sown soil and in the post-emergence tests untreated soil bearing seedling plants were used as controls.

The herbicidal effects of the compounds were assessed visually seven days after spraying the foliage and drenching the soil and eleven days after spraying the soil, and were recorded on a 0-9 scale. A rating 0 indicates no effect on the treated plants, a rating 2 indicates a reduction in fresh weight of stem and leaf of the plants of approximately 25%, a rating 5 indicates a reduction of approximately 55%, a rating 9 indicates a reduction of 95% etc.

The results of the tests are set out in Table 2 We claim as our invention: 1. A compound having a structure defined by the formula where R, is NHZ in which Z is hydrogen. alkyl of up to 6 carbon atoms, cyclohexyl, b enzyl, phenyl or phenyl substituted by a fluorine atom, by one or two chlorine atoms, by one or two alkyl groups of l-2 carbon atoms or by alkoxy of l-2 carbon atoms; R is hydrogen or alkyl of l-6 carbon atoms; R, :is alkyl of l-6 carbon atoms; and R 2. A compound according to claim 1 where R is NHZ in which 2 is phenyl, fluorophenyl, chlorophenyl, dichlorophenyl, tolyl, dimethylphenyl, or methoxyphenyl; R is hydrogen or methyl; R is methyl, ethyl or propyl and R is benzyl.

3. A compound according to claim 2 where R. is NHZ, Z is phenyl, and R is methyl.

4. 4-Benzyloxymethyl-4-ethyl 2-methyl-l,3- dioxolane-2-(N-phenylcarboxamide).

5. 4-benzyloxymethyl-2,4-dimcthyl-l.3-dioxolan-2- (N-phenylcarboxamide).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3,862,959

DATED 1 January 28, 1975 |NVENT0R(5) 1 Peter Kirby and Eirlys Rn Isaac It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, last line, after R add is benzyl Signed and sealed this 29th day of April 1.975.

(SEAL) test: 0. MARSHALL DANN RUTH C. MASON Couunissioner of Patents Attesting Officer and Trademarks 

2. A compound according to claim 1 where R1 is -NHZ in which Z is phenyl, fluorophenyl, chlorophenyl, dichlorophenyl, tolyl, dimethylphenyl, or methoxyphenyl; R2 is hydrogen or methyl; R3 is methyl, ethyl or propyl and R4 is benzyl.
 3. A compound according to claim 2 where R1 is -NHZ, Z is phenyl, and R2 is methyl.
 4. 4-Benzyloxymethyl-4-ethyl-2-methyl-1,3-dioxolane-2-(N-phenylcarboxamide).
 5. 4-benzyloxymethyl-2,4-dimethyl-1,3-dioxolan-2-(N-phenylcarboxamide). 